2202: On the possibly the explosions were a terrorist attack, Mr Davis says: "You can draw your own conclusion."

2202: There had been no warnings or intelligence suggesting this might happen before the race, Mr Davis says.

2202: Massachusetts Governor Deval Patrick says: "We are asking that people stay out of crowds and calmly make their way home or to a hotel."

2201: The FBI and other federal agencies are aiding in the investigations, officials say.

2200: Ed Davis, Boston's commissioner of police, adds: "People should be calm but understand that this is an ongoing event and we need all the information available to us."

2159: "Bags and parcels" left behind by evacuating runners are all being treated as "possible incendiary devices", Boston police say.

2158: Boston officials say there has been a "third incident" at the JFK Library but are not sure if it is related to the two other explosions.

2156: US Homeland Security Secretary Janet Napolitano says she is directing her agency to provide "whatever assistance" is necessary in the wake of the explosions.

2154: Pictures on Twitter show casualties lying on the pavement on Boylston Street and debris blowing around them. Another photograph appeared to show participants running down the street at the moment an explosion created a fireball.

2153: The marathon attracts huge numbers of spectators and this year's race had about 25,000 registered runners, with about 374 from the UK.

2152: Mario Cacciottolo adds: "Small groups of runners and their supporters are huddling together, pooling information and trying to find out just what has happened."

2204: The Boston Bruins hockey game against the Ottawa Senators has been cancelled, the Boston Globe reports.

2203:

Police Commissioner Ed Davis says the next briefing will take place in two hours' time.

2202: On the possibly the explosions were a terrorist attack, Mr Davis says: "You can draw your own conclusion."

2202: There had been no warnings or intelligence suggesting this might happen before the race, Mr Davis says.

2202: Massachusetts Governor Deval Patrick says: "We are asking that people stay out of crowds and calmly make their way home or to a hotel."

2201: The FBI and other federal agencies are aiding in the investigations, officials say.

2200: Ed Davis, Boston's commissioner of police, adds: "People should be calm but understand that this is an ongoing event and we need all the information available to us."

2159: "Bags and parcels" left behind by evacuating runners are all being treated as "possible incendiary devices", Boston police say.

2158: Boston officials say there has been a "third incident" at the JFK Library but are not sure if it is related to the two other explosions.

2157:

Ambulances line the streets in Boston

2156: US Homeland Security Secretary Janet Napolitano says she is directing her agency to provide "whatever assistance" is necessary in the wake of the explosions.

2154: Pictures on Twitter show casualties lying on the pavement on Boylston Street and debris blowing around them. Another photograph appeared to show participants running down the street at the moment an explosion created a fireball.

2153: The marathon attracts huge numbers of spectators and this year's race had about 25,000 registered runners, with about 374 from the UK.

2152: Mario Cacciottolo adds: "Small groups of runners and their supporters are huddling together, pooling information and trying to find out just what has happened."

2152: Ed Davis, Boston's commissioner of police, says the explosions occurred at 14:0 EDT. He says simultaneous explosions occurred 50-100 yards apart. All casualties have been removed from the scene he says.

2152: Mario Cacciottolo, BBC News, Boston says: "The music turned off and the mood changed quickly. Every other person turned to their mobile phone to reassure loved ones, and while the sun continues to shine, the crowds have dissipated fast and police are everywhere."

2149: Mario Cacciottolo, BBC News, Boston says there was a carnival-like atmosphere in Boston's Washington Square as the race ended but the mood quickly changed as news of the explosion filtered through.

2204: The Boston Bruins hockey game against the Ottawa Senators has been cancelled, the Boston Globe reports.

2203:

Police Commissioner Ed Davis says the next briefing will take place in two hours' time.

2202: On the possibly the explosions were a terrorist attack, Mr Davis says: "You can draw your own conclusion."

2202: There had been no warnings or intelligence suggesting this might happen before the race, Mr Davis says.

2202: Massachusetts Governor Deval Patrick says: "We are asking that people stay out of crowds and calmly make their way home or to a hotel."

2201: The FBI and other federal agencies are aiding in the investigations, officials say.

2200: Ed Davis, Boston's commissioner of police, adds: "People should be calm but understand that this is an ongoing event and we need all the information available to us."

2159: "Bags and parcels" left behind by evacuating runners are all being treated as "possible incendiary devices", Boston police say.

2158: Boston officials say there has been a "third incident" at the JFK Library but are not sure if it is related to the two other explosions.

2157:

Ambulances line the streets in Boston

2156: US Homeland Security Secretary Janet Napolitano says she is directing her agency to provide "whatever assistance" is necessary in the wake of the explosions.

2154: Pictures on Twitter show casualties lying on the pavement on Boylston Street and debris blowing around them. Another photograph appeared to show participants running down the street at the moment an explosion created a fireball.

2153: The marathon attracts huge numbers of spectators and this year's race had about 25,000 registered runners, with about 374 from the UK.

2152: Mario Cacciottolo adds: "Small groups of runners and their supporters are huddling together, pooling information and trying to find out just what has happened."

2152: Ed Davis, Boston's commissioner of police, says the explosions occurred at 14:0 EDT. He says simultaneous explosions occurred 50-100 yards apart. All casualties have been removed from the scene he says.

2152: Mario Cacciottolo, BBC News, Boston says: "The music turned off and the mood changed quickly. Every other person turned to their mobile phone to reassure loved ones, and while the sun continues to shine, the crowds have dissipated fast and police are everywhere."

2149: Mario Cacciottolo, BBC News, Boston says there was a carnival-like atmosphere in Boston's Washington Square as the race ended but the mood quickly changed as news of the explosion filtered through.

"The crowds have dissipated fast and police are everywhere."

2143: A witness wrapped in a Mylar blanket tells ABC News he saw "the garbage can explode"

2142: The BBC has collected photos from the aftermath of the Boston Marathon explosions this afternoon

2130: Local ABC reporter Liam Martin tweets: "Director of emergency services at Mass General describes injuries as "from a war zone"

2130: Cherie Falgoust was waiting for her husband, who was running the race. She tells AP: "I was expecting my husband any minute. I don't know what this building is... it just blew. Just a big bomb, a loud boom, and then glass everywhere. Something hit my head. I don't know what it was. I just ducked."

2129: US paralympian Tatyana McFadden, who won the women's wheelchair race, tweets: "I'm okay my family and teammates are okay. Please please pray for those who were running and got hit by the bomb. Pray 4 family's-friends."

A burned Saudi college student, who is recovering in a local hospital, is a person of interest but not a suspect. Authorities searched his upscale appartment in Boston overnight and took some items away. I noticed that US TV channels were broadcasting live interviews of the victims today from hospital.

Question: Why an Arab channel such as Al-Jazeera is not interviewing this Saudi student?

No significant leads so far. Experts say it may be a home grown stuffer.

The mass killings of very young children at Sandy Hook was much more devastating and much more tragic but the incident was NEVER refered to as Terrorist incident and no special coverage was given like we aww for this marothon incident.